1. Field of the Invention
The present invention relates to a method and apparatus for inspecting biological samples. This invention has particular application to the automated inspection of material prior to sampling for analysis purposes, and for illustrative purposes the invention will be further described with reference to this application. However, it is envisaged that this invention will find use in other applications, such as for sample identification, sample integrity assessment.
In particular, although not exclusively, the invention relates to a method of inspection of biological samples for selecting a portion of each sample for further analysis, and to an inspection apparatus for carrying out the method.
2. Discussion of the Background Art
Biological samples are often collected on absorbent media such as filter paper. Materials that have been collected and retained on a medium may need to be subject to several analyses, sometimes after storage for extended periods. Typically, portions of an original sample of material are periodically removed from the medium for analysis, such as an assay. Furthermore, the original sample may not be deposited evenly over the media, such as may occur during manual collection. Biological samples such as blood and other anisotropic materials may undergo some partitioning as a consequence of selective adsorption by the medium (such as migration of plasma away from the pigment).
It is important, if an analytical test is to be valid, that the portion subject to assay is either representative of the whole sample, or is selected to be the best part of a variable sample. However, if the sample is not homogeneously deposited on the media, the testing of some small portions of the sample may give different results to the testing of other small portions.
It may be equally important that sufficient sample material from the sample deposited on the media is tested.
In taking a sample for analysis, a typical method includes a small portion of the sample to be tested being punched out of filter paper on which the specimen is absorbed by a circular punch, resulting in one or more circular sample disks with diameter of between 1.2 mm and 6 mm.